Hope you don't mind... here is my suggestion (just a quick sketch) for a simple page for managing email/ebot subscriptions. Just sorted by user, and you could also add bulk options to turn off everything in each section. Just have everything off by default to start with and then users can add things one by one to cut down that load on the server, which is an understandable concern.

It would also need nice bar at the top with the usual search boxes, drop down boxes etc.

Frequency Gallery  |  Frequency Store